Soil Moisture Experiment (SMEX)

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Data Set Access


The Soil Moisture Experiment field campaigns (SMEX02 , SMEX03 and SMEX04-NAME) are part of the Advanced Microwave Scanning Radiometer evaluation (AMSR-E) campaign and a continuation of the Southern Great Plains field campaigns (SGP99). SMEX studied soil moisture remote sensing techniques and hydrological processes affecting the energy flux at the land-atmosphere boundary. SMEX02 was carried out near Ames, Iowa during the summer of 2002. SMEX03 was carried out in parts of Georgia, Alabama, Oklahoma, and Brazil. SMEX04-NAME will be conducted in Arizona and Mexico.

The GPS Bistatic Radar Delay Mapping Receiver (DMR) instrument participated in 2002 and 2003 flights over the SMEX study areas. In 2002, the receiver was mounted on the NCAR C-130 along with the JPL PALS instrument. In 2003, the receiver was flown on the NASA P-3 with the NOAA PSR instrument. GPS signal reflections were collected using the standard hemispherical right hand circularly polarzied (RHCP) antenna mounted on the roof of the aircraft, and a reversed polarization LHCP hemispherical antenna mounted on the belly. The reflections collected in 2002 were from flat agricultural land with mostly corn and soybean crops in mid-development. The reflections collected in 2003 were from agricultural land in Georgia and Alabama, along with grassland in Oklahoma. The primary objective was to collect land reflections for sensitivity of the reflected GPS power to temporal and spatial soil moisture and foliage attenuation.

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Spatial and Temporal Coverage

In 2002, Data were collected throughout the Walnut Creek Watershed near Ames, Iowa (93.800W 93.400W 41.915N 42.005N). In 2003, data were collected in Georgia, Alabama, Oklahoma, and Brazil. Spatial resolution of these data is variable depending on airborne height and scattering regime (specular or rough). At 1 km height, 20 deg incidence angle, first Fresnel zone is a 30 m spot, while first range bin is a 1.5 km spot. At 10 km height 20 deg incidence angle, first Fresnel zone is an 80 m spot, while the first range bin is a 5.0 km spot. Data were collected 25, 27 June and 1, 2, 5-8 July 2002. Data were also collected 24, 25, 27, 30 June and 2, 3, 5, 7, 12-15, 17, 18 July 2003.

Data Format and Structure

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Analysis Results

Investigator Contacts

External Links

Last modified: Wednesday, 04-May-2005 15:21:30 MDT